In the English language a sentence is a relationship between a subject and an object: someone or something that acts and someone or something acted upon, an "I" or "She" or "He" or "We" or "they" and a "you," "him," "her," "them," or noun (the horse, the day, the summer).
I love you. I hate you. I walk toward you. I follow you. Or, somewhere else in time: I loved you, I will hate you.
The sentence can become a fork in the road or a journey or a story, as it did when I walked with you until we came to the end of the road where we were met by the postman continuing on his way, followed by a mother duck and her ducklings. If you diagram a sentence it becomes a tree.
We speak in trees so that we can understand each other.
Sometimes this "you" is an object: I dropped the ball. She fell off the chair. The bird flew into the sky. Sometimes the "you" is made into an object: "I hit the man."
A complete sentence creates: a relationship, a territory, a violence, a piece of time. It has an ending. A period is over: period. A space is closed: edge.
Punctuation gestures. What kind of pause? What is the hand shaping this sentence?. If the sentence is incomplete that relationship is at risk: interrupted, unfound, open to the elements, without body.
The sentence is a desire for contact. It must end. It cannot end. A sentence carries a voice calling for response.
The sentence is a body gesturing, articulating.
To sentence is to declare a punishment. A life sentence is a life long punishment. A death sentence is punishment by death. The sentence is about sentience.
Is the sentence disappearing? Are we inside a sentence we can no longer find? Where do I meet you?
Write a poem in which each line is a complete sentence. Keep writing and notice what begins to happen. Try short sentences. Try long sentences. Try alternating short and long sentences.